Bearing and the like



vof the lead in relatively large globules.

Copper Patented July 3,1945

asians ammo AND "me uns Franz It. Hensel, Indianapolis, Ind., assignor to P. R. Mallory & Co., Inc., Indlanapol|s,`lnd., l.

corporation of Delaware 'Application December zo, 1941, serial rra-423,822

z clause. (ol. aos-7242i' solutions over the entire `range of proportions inl No Drawing.

This invention relates to bearings. i

An object of the present invention is to improve copper base bearings. l

Other objects of the invention will be apparent from the following description taken in connection with the appended claims.

The present invention comprises the combination of elements, methods of manufacture, and the product thereof brought out and exemplified in the disclosure hereinafter set forth, the scope of the invention being indicated in the appended claims.

While apreferred embodimentof the invention is described herein,.it is contemplated that considerable variation may be madey in the method of procedure and the combination of elements without departing from the spirit of the invention.

In the prior art, bearings have been formed of copper or bronze containing various percentages of lead. While such bearings have performed with considerable satisfaction and have relatively high strength combined with low friction qualities, such` bearings have not always been satisfactory in all particulars. .For example, it has been dimcult to vobtain uniform distribution of lead throughout the copper matrix and this' has erties.

Bearings of the type described ar frequently bonded to a steel backing for additional strength and support. Such bonding requires the application of relatively high temperatures for a comparatively long period of time. Such prolonged heating, however, interferes with the proper distribution of lead and promotes the accumulation Such large size lead inclusions are not as effective in promoting a bearing of uniformly low friction as are uniformly distributed 'ne particles of lead.

Lead is also subject to a certain amount of oil corrosion when used in bearings.

- dicated above. Neither the lead nor the thallimn forms solid solutions with the copper to any substantial extent and hence the bearings produced from the above composition are characterized by fine particles of lead-thallium alloy distributed throughout the bearing at the grain boundaries of the copper base matrix. This lead-thallium alloy has a higher melting point than either pure resulted in some non-uniformity of bearing prop- 7 lead or pure thallium over a considerable range of compositions.

The lead-thallium alloy is also very acid resistant and hence contributes to the production of a bearing which is resistant to corrosion from oil or other sources. In fact, leadthallium alloys containing 20 to 65% thallium belong to the most insoluble of known alloys.

Neithe;- the lead nor the thallium affects the properties of the copper matrix. On the other hand, the solid solution of thallium and lead has a higher resistance to deformation and fatigue than either pure lead or pure thallium and hence these properties contribute to the production of a bearing of greater strength and resistance to deformation. I

Photomicrographs of cast bearings produced from copper, lead and thallium indicate that the lead-thallium solid solution seems to have a deflnite advantage in promoting a more uniform distribution of the lead-thallium particles than is obtainable with either element alone.

One special. combination having especially de-i sirable properties for some uses comprises a copper base containing distributed particles vof leadthallium alloy having the formula PbTlzi` in which The present invention contemplates a, copper i base bearing of improved characteristics formed of a copper base metal composition containing both thallium and lead. It is contemplated that the bearing may be formed of metal compositions within the following range of proportions:

Thallium percent-- l to 34 Lead do 1 to 34 and constituting at least 65% of the composition- Substantially the balance,

Lead and thallium form complete series of solid o5 the ratio of thallium to lead is approximately 2 to 1 in atomic percentages.

It is of ,advantage in some cases to improve the characteristics of the copper by the addition of relatively small quantities of materials which act either as grain refiners or, hardening ingredients or both. One of the most useful materials is tin which may be present in proportions varying from .1 to 10% by weight of the composition.

The tin increases the hardness and strength of the copper base and increases the resistance of the bearing to fatigue.

Instead of tin, silver may also be used to ing crease the strength of the copper base and it does so without greatly decreasing the thermal conductivity of the bearing. Silver also appears to provide a nucleus-forming ingredient ywhich promotes the fine and homogeneous distributionof, I the lead-thallium phase. Nickel and manganese also act as grain refiners and improve the physical properties of the bearing.

In order to still further improve the corrosion resistance of the alloy it has been found of advantage in some cases to apply a coating of indium preferably by electroplating the surface of the finished bearing and then heat treating the bearing to diffuse the indium into the surface. Indium, lead and thallium form a series of solid solutions which are highly corrosion resistant. The indium plating can be diiused into the leadthallium at slightly elevated temperatures such as 300 F.

It may also be of advantage in preparing the bearing alloy to add small amounts of alkali or alkaline earth metals as deoxidizers. These metals also eiect grain reilnement.

Alloys of the following compositions, produced by melting the copper, adding the lead and thallium and thoroughly stirring the molten alloy followed by casting and rapid chilling of the bearing, showed a uniform :fine dispersion of the leadthallium solid solution in the grain boundaries of the copper matrix:

l l Per cent Thallium 9.62 Lead 9.64 Copper Balance 2 Per cent Thallium 10.71 Lead 9.65 Tin 3.02 Copper Balance The alloys can be produced by rst melting the copper, then adding the thallium and lead to the melt, thoroughly stirring and chill casting as described above. In some cases the bearing can be forged from the alloy. Bearings can also be provided on steel backing shells by centrifugally casting or ordinary casting. Likewise, the bearings can be preformed and then secured to steel backing shells by welding, brazing or other means.

The bearings of the present invention can also be made by other manufacturing methods, such as by mixing the metal powders, pressing and sintering the mixture.

Another method of manufacture comprises spraying mixed molten particles of copper, thallium and lead onto the surface to be provided with a bearing by a metal spray gun.

This application is a continuation-impart of my co-pending application for Bearings, Serial No. 230,203, filed September 16, 1938.

While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is:

l. A bearing formed of a metal composition of l to 34% thallium, l to 34% lead and the balance substantially all copper, said copper constituting at least of the composition.

2. A copper base bearing formed of a copper base matrix and small particles of lead-thallium alloy distributed in the bearing at the grain boundaries of the copper base matrix, said thallium forming 1 to 34% byweight of the bearing composition, said lead forming 1 to 34% of the bearing composition and said copper constituting at least 65% of the composition.

FRANZ R. HENSEL. 

